Amphibians at risk, and perhaps not just them

Much has been written about the dramatic decline of the world’s amphibians, and one doesn’t have to be especially fond of frogs to recognize that it’s a problem worthy of real attention: amphibians are especially sensitive to pollutants and other changes to their environment and, like “canaries in the mine”, the decline of their populations may presage hazards and risks that could eventually negatively impact whole ecosystems and all the species that depend on them.

Added to the environmental factors already wiping out whole species, over the past decade a deadly fungal disease (chytridomycosis or chytrid) has resulted in the extinction of at least 200 amphibian species and now threatens fully one-third of the world’s frogs, toads and salamanders (40% of whom are already in decline). No one appears to be completely certain how or why this actually very ancient fungus has now turned into such a risk to amphibians, but judged in terms of the ability to drive whole species to extinction this is now considered the worst infectious disease to ever hit any vertebrate animals.

Close to a worldwide epidemic (the problem now exists on every continent with the exception of Antarctica), one of the close-to-home communities now seriously impacted are the Sierra Nevada Yellow Legged Frog of Sequoia and Kings Canyon National Parks. A hundred years ago, these frogs were so plentiful in the area that tourists complained about not being able to walk without trampling on them. Not so today. In fact, these frogs were already in dire trouble as the result of California Fish and Game’s longstanding practice of releasing baby trout in the lakes of the area for fishermen, a practice which had already wiped out close to half of the area’s Yellow Legged Frog populations (fingerling trout apparently enjoy a good meal of tadpole).

In the effort to save the last surviving frogs, Fish and Game has now begun to catch and remove the trout they themselves put into these waters, acknowledging the contradiction of attempting to be (in the words of a Department biologist) “both ecological stewards and recreational purveyors.” Many of us wish they could focus exclusively on the first of those two roles, a sentiment in fact shared by many Fish and Game employees when you get them off the record.

And alongside Fish and Game’s about face, a San Francisco State University professor of biology, Vance Vredenburg, is now treating the small surviving frog population with a bacterium that has proven safe for the frogs but deadly to the fungus. Time, and perhaps not much of it, will tell….